After the harvest
Preserving mushrooms: drying, powder, fermenting
Wild mushrooms taste best fresh. If you find more than fits on one plate, you can preserve them for months – four ways, and what matters along the way.
Four ways
All four suit firm-fleshed species such as porcini, bay bolete or horn of plenty. Very watery mushrooms need more patience when drying.
Cook them fresh
Keeps 1–2 days in the fridge. Clean them on the day you find them and cook thoroughly within 24 hours – most wild mushrooms are not tolerated raw.
Dry them
Keeps for months without refrigeration. Slice thinly and dry with plenty of airflow until they snap instead of bending.
Grind to powder
Grind fully dried mushrooms fine – an umami seasoning for sauces, soups and risotto.
Ferment them
Lacto-fermented like sauerkraut – still a newer technique for wild mushrooms, with its own tangy flavour.
Drying, step by step
- PrepareClean them dry, slice 3–5 mm thick. Cut away maggoty or soft parts generously – they do not dry well.
- DryStrung up on a thread, in a dehydrator at 40–50 °C, or in the oven on the lowest setting with the door ajar – one to three days depending on method and humidity. Direct sun works too but fades the colour a little.
- Check and storeDone when slices snap instead of bending. Store airtight, dark and cool – they keep for over a year. Before cooking, soak 20–30 minutes in warm water and use the soaking liquid too, it is full of flavour.
Good for drying: porcini, bay bolete, horn of plenty, birch bolete. Chanterelles and button mushrooms hold more water and take longer.
Grinding to powder
Only use pieces that are completely dry – any moisture left will go mouldy in the powder. Grind fine in a spice or coffee grinder and sieve out coarse stem or cap bits. Store airtight and dark. A teaspoon is enough to add depth to sauces, soups or risotto – especially good made from porcini.
Fermenting
Lacto-fermentation, as with sauerkraut: blanch the mushrooms briefly (2–3 minutes), then submerge them in a brine (about 2% salt by weight of water), weigh them down under the liquid, and let them ferment at room temperature for several days to two weeks until pleasantly sour. Refrigerate afterwards. Clean jars and hands matter; if you see mould, a foul smell, or nothing happens: discard it.
Fermenting is a newer, still less standardised method for wild mushrooms. For exact quantities, a dedicated fermentation guide is worth consulting.
Drying, powdering or fermenting does not make a poisonous mushroom edible and does not reliably change its toxicity. Only process mushrooms you have identified with absolute certainty.